Acceleration and force

Our law of inertia was:

A body that is subject to no external forces will not accelerate.

So, does that mean that if you push or pull ("exert a force") on something it *will* accelerate? What's the relationship of force and acceleration?

Acceleration

Acceleration = change in velocity (either speed or direction) over time.

In the following examples,

  1. Say whether there is acceleration or not,
  2. Identify the force, or explain why there's no force...

Acceleration?

See: HHSTT rocket sled video.

Acceleration?

Orbit of the Hubble Space Telescope around the earth.

hubble orbit

Acceleration?

See: Crash test video.

Acceleration?

A car...

  1. Moving along a straight, level road at 120 km/hr?
  2. Moving along a straight, level road and slowing from 120 km/hr to 70 km/hr?
  3. Rounding a curve at a steady 50 km/hr?
  4. Moving uphill along a straight incline at 50 km/hr?
  5. Rounding a hill top at 50 km/hr?

Acceleration!

These things all mean "Acceleration" in Physics-speak:

  • speeding up
  • slowing down
  • turning

What 3 acceleration devices can a car driver control?